Are “Nuts” Actually Nuts?
Botanically speaking, most of the “nuts” we eat are actually fruit seeds (most culinary nuts are not botanical nuts).
True botanical nuts include the acorn, chestnut, and hazelnut. All other common “nuts” are drupe, gymnosperm, or angiosperm seeds (fruit seeds). Culinary nuts that are botanically fruit seeds include the almond, which is related to the apricot, and the peanut, which is part of the legume or bean family.
What Makes a Nut a Nut?
Culinarily a wide array of dried seeds are called “nuts.” Most culinary nuts can be described as “an edible fruit composed of a hard shell and a seed.” Botanically for a “nut” to be a “true nut.” the shell must not open to release the seed; the shell must be indehiscent.
The dictionary version of Nut: “a fruit consisting of a hard or tough shell around an edible kernel.” 
Difference Between Botanical Nuts and Culinary Nuts?
- Botanical Nut: Botanically a nut is a fruit. The fleshy part of the fruit, it’s seed, the shell of the seed, and everything that isn’t woody or green is “fruit” (including most of what we call beans and nuts in the kitchen).
- Culinary Nut: Any nut or fruit seed used as a nut in the kitchen.
WTF?! is a nut? From the awesome DNews.
FACT: Of all the common nuts only acorn, chestnut, kola, and hazelnut are botanically nuts, the rest are seeds surrounded by fruit. Despite this, they are all “culinary nuts.” In other words: If you are in the kitchen, it’s a nut; if you are in the lab, it’s either a true nut or a type of seed. It is almost always a fruit seed. Pine nuts, for example, don’t have “a carpel” or a fleshy fruit component.
The Types of Nuts (Types of Culinary Nuts)
Below we cover each type of nut and discuss its botanical order.
Culinary Nuts are Divided into Four Categories:
- True, or botanical nuts are dry, hard-shelled, uncompartmented fruit that does not split on maturity to release seeds. Including the acorn, chestnut, and hazelnut. True nuts are the ones we think of squirrels as eating. The Kola nut is a true nut, which provides the “cola” flavor for popular soft drinks.
- Drupes Seeds are fleshy fruit surrounding the stone or pit, which contains a seed; these are sometimes used as culinary nuts. Drupes include coffee, mango, olive, most palms (including date, coconut and oil palms), pistachio, and all members of the genus Prunus, including the almond, prune, apricot, cherry, damson, nectarine, peach, and plum. These nuts are the enclosed seed of fruit. They include coffee, apricots, and almonds.
- Gymnosperm Seeds are naked seeds, with no enclosure. Including pine nuts and ginkgo nuts. These nuts grow on trees and are seeds.
- Angiosperm Seeds are unenclosed seeds within a larger fruit. These include the peanut, soybean, macadamia, and Brazil nut. Seeds in this family are often related to beans. Soybeans and peanuts are legumes belonging to the bean or pea family.
Common Culinary Nuts and their Properties:
- Almond: The almond is the seed of a fruit that grows on a tree from the genus Prunus. It’s related to the prune and apricot.
- Cashew: The cashew is the seed of an accessory fruit, which makes it a relative of the strawberry and in the same family as poison ivy (Anacardiaceae).
- Chestnut: A Chestnut is a nut. Sweet chestnuts, unlike most nuts, are high in starch and sugar but not fat. Perhaps this is why they work well roasted on an open fire.
- Coconut: Coconuts are not botanical nuts, but it they are culinary nuts. The fleshy edible part is inside the shell.
- Hazelnut: A hazelnut seed that grows into a large shrub. With some culinary magic, it turns into Nutella.
- Macadamia: These are angiosperm seeds, high in omega three, but toxic to dogs.
- Peanut: The peanut is a legume from the bean family. Its fruit grows underground where it produces a natural fertilizer for the plant. Yes, that right, beans are fruit; the musical fruit song wasn’t lying.
- Pecan: A Pecan is a type of drupe seed from a hickory tree. It is the only major nut tree native to North America.
- Pine nut: A Pine nut is a type of gymnosperm seed that grows on a pine tree and isn’t surrounded by fruit.
- Pistachio: Another drupe seed is the Pistachio. It’s notable for being part of the Anacardiaceae family, which includes poison ivy, sumac, mango, and cashew.
- Walnut: A walnut is the nut of any tree of the genus Juglans. There are many types of Walnuts. Like other tree nuts, they spoil quickly.
- Acorn: The tree nut that squirrels eat is a true nut. Squirrels likely appreciate the fact they don’t have to dig through layers of fleshy fruit to get to it.
- Beechnut: They grow on beeches, which are a large family of trees. Squirrels love this nut. It is seldom used as a food source except by indigenous people.
- Kola nut: That is where “kola,” the soft drink flavor, comes from. Coffee, chocolate, and kola all grow as fruit seeds.